Permanent magnetic pulley



Oct. 4, 1955 S. G.` INJESKI, JR

PERMANENT MAGNETIC PULLEY Filed Feb. 12, 1954 2 Sheets-Sheet l INVENTOR.

A T TOR/vens.

Oct. 4, 1955 s. G. INJESKI, JR

PERMANENT MAGNETIC PULLEY 2 Shets-Sheet 2 Filed Feb. l2, 1954 United States Patent C) PERMANENT MAGNETIC PULLEY Stanley G. Injeski, Jr., Milwaukee, Wis., assigner to Dings Magnetic Separator Co., Milwaukee, Wis., a corporation of Wisconsin Application February 12, 1954, Serial No. 409,892 1o claims. (c1. 209-219) This invention relates in general to improvements in the art of magnetic separation, and relates more specifically to improvements in the construction and operation of permanently magnetic pulleys each of which is especially adapted to separate magnetic materials from non-magnetic substances comprising bulk layers of limited thickness bought into proximity with the periphery of the revolving pulley.

The primary object of the present invention is to provide a permanent magnetic pulley which is simple in construction and highly eiective in use.

As shown and described in U. S. Patent No. 2,535,719, granted December 26, 1950, it has heretofore been proposed to provide a magnetic pulley for removing magnetic material from layers of non-magnetic substances presented to the pulley periphery and within which the magnetic materials are embedded, and which pulley cornprises an annular series of permanent magnets radiating from a common axis and having their inner ends snugly contacting a polygonal magnetic hub while their outer ends are provided with magnetic pole-shoes separated by non-magnetic spacers which cooperate with the pole-shoes to form the pulley periphery. While this patented pulley structure has proven fairly satisfactory in actual commercial use, the pole-shoes at the outer ends of the permanent magnets were relatively wide as compared to the width of the intervening spacers, thus causing excessive concentration of the magnetic ux directly adjacent to the magnet poles and resulting in considerable non-effective magnetic leakage between adjacent poles. This prior pulley structure also embodied a polygonal hub coacting with the inner ends of thepermanent magnets, and since these magnets are preferably formed of very hard material such as Alnico metal which must be ground to fit adjoining parts, it was found rather difcult to obtain flat surface contact between the magnet blocks and the pulley hub.

It is therefore an important object of my present invention to provide an improved magnetic pulley assemblage of the general type shown in said prior patent, but wherein far more elfective distribution of theavailable magnetic ux is obtained and enhanced efliciency results by considerably diminishing the width of the successive magnet poles and by correspondingly increasing the width of the intervening non-magnetic spacers or gap covers.

Another important object of this invention is to provide an improved permanent magnetic pulley unit embodying magnet blocks radiating from a magnetic hub and having outer spaced poles coacting with arcuate' gap covers, all parts of which may be readily constructed and assembled to produce durable and highly etiicient pulleys.

A further important object of the invention is to provide an improved magnetic pulley structure comprising relatively few simple parts which may be assembled to provide pulleys of various sizes, and in which magnetic leakage losses are reduced to a minimum so that the available magnetic flux will act most effectively upon magnetic l along the line 1 1 of Fig. 2;

ice

materials embedded in layers of bulk substances of relatively great thickness. f'

Still another object of my invention is to provide various improvements in the construction of permanent magnetic pulleys whereby the manufacture .thereof is facilitated while their efiiciency is enhanced to a maximum.

These and other objects and advantages of the invention will be apparent from the following detailed description.

A clear conception of the features constituting ,the present improvements, and of the construction and operav tion of Vseveral commercial permanent `magnetic pulleys embodying the same, may be had by referring to the drawings accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

Fig. l is a front sectional end view of one of the improved magnetic pulleys having permanent magnets provided with separate pole-shoes of limited width, showing the flux field pattern of one of the magnets in dot-anddash lines, and the transverse section having been taken Fig. 2 is a longitudinal section through an end fragment ofthe magnetic pulley of Fig. 1, the section having been taken along the lines 2 2 of Fig. l;

Fig. 3 is a transverses vertical section through a moditied magnetic pulley embodying the invention but having the separate pole-shoes omitted, the section being taken along `the line 3--3 of Fig. 4;

Fig 4 is a fragmentary longitudinal section taken through one end of the modified pulley, along the irregular linek4-4 of Fig. 3; and

Fig. 5 is a perspective view of one of the improved permanent magnetic pulleys, especially depicting the modiiied pulley but simulating the other.

While the invention has been shown and described herein as having been applied to pulleys of relatively short overall length embodying only a few annular series of permanent magnets, it should be understood that the improved features are also adapted to be utilized in pulleys of greater or lesser diameter having more or less numbers of these annular magnet series each embodying a greater or lesser number of magnets; and it is also contemplated that specific descriptive terms employed herein be given the broadest possible interpretation consistent with the disclosure.

Referring to Figs. l and 2 of the drawings, the improved permanent magnetic pulley shown therein comprises in general, an elongated hollow cylindrical magnetic hub 8 having opposite end rings 9 secured thereto and being provided with supporting inserts 10 at its opposite ends; several longitudinally alined annular series each consisting of eight radially disposed permanent magnets 11 the inner ends of which snugly engage the outer periphery ofk the hub 8 and the outer end of each of which is tapered and likewise engages an elongated magnetic pole-shoe 12 each coacting with all of the alined magnets 11 of the several series; an annularV series of arcuate gap covers or spacers 13 interposed between the successive lpole-,shoes 12 of the magnets 11 and each having opposite edge anges 14 extending beneath the adjacent pole-shoes 12; stud bolts 1 5 secured to the hub 8 between the successive alined magnets 11 and clampingly engaging the pole-shoes 12 to clamp the adjacent magnets 11 to the hub 8 and to simultaneously hold the spacers 13 in place; end heads 16 slidably embracing the .inserts 10 andk coacting with the' 9 may be welded to the hub 8 and secured to the hub inserts 10 by means of cap screws 19, see Fig. 2. The hub 8 may be of any desired length depending upon the length of pulley desired and the number of annular magjnet series that are to be embodied, and the hubV inserts 9 may be keyed or otherwise secured to a central pulley mounting shaft in an obvious manner. The magnets 11V are preferably formed of metal such as Alnico' having highk magnetic energy and capable of being intensely magnetized, and since this metal is exceedingly hard andv diflicult to machine with cutting tools, the inner ends of the cast magnet blocks are preferably ground to snugly engage the external peripheral surface of the hub 8 as shown in Figs. l and 2. The tapered outer ends of the magnets 11 are also preferably ground so as tolikewise engage the inner surfaces of the adjacent pole=shoes 12 which are also formed of highly magnetic material such as ordinary steel and project laterallyslightly beyond the tapered outer magnet ends.

The arcuate gap covers or spacers 13 should be formed ofnon-magnetic metal such as aluminum or brass and besides' having their edge flanges 14 disposed beneath the overhanging edges ofthe adjacent pole-shoes 12, these spacer plates should also engage the opposite edges of the pole-pieces and should cooperate with the outer pole-'shoe surfaces to provide a substantially continuous outer peripheral surface for the pulley, see Fig. l. Both the spacers 13 and the pole-shoes 12 extend throughout the effective length of the pulley, and the radial stud bolts 1S which are located between the successive alined magnets 11 serve to simultaneously clamp the spacers 13, poleshoes 12 and the magnets 11 against the hub 8, while the longitudinal bolts 17 clamp the pole-shoes 12 and spacers 13 between the end heads 16. These end heads 16 are also preferably formed of non-magnetic metal such as aluminum or brass, and are slidab'ly engageable with the adjacent hub inserts 10 so' that the entire pulley unit may be assembled or dismantled by merely manipulating the stud bolts 15, the bolts 17 and the cap screws 19.

A very important' feature of the present invention is the proper distribution of the magnetic ilux so as to insure most eflicient utilization of the magnetic energy and to eliminate undesirable magnetic leakage losses to the greatest possible extent, and this feature involves the relative proportioning of the widths of the magnet poles and of the non-magnetic gap covers or spacers 13. As shown in Fig. l, wherein pole-shoes 12 constitute a part of the magnet poles, these shoes are considerably less than one-third of the effective widths of the spaces or gaps between the successive poles. It has been discovered that this reduction in width of the poles relative to the intervening gaps between successive poles, produces an entirely different flux field pattern from that produced by an assemblage such as shown in Patent No. 2,535 ,719 wherein the magnet poles are wider than' the intervening spaces between adjacent poles. With the structure shown in the patent, the strongest zone of magnetic influence was created between the adjacent pole-shoes and the highest gauss readings were obtained in these zones, whereas with the present improved pulleys the highest gauss readings are obtained in the zones directly adjoining the pole-shoes 12, thereby producing mosteil'ective distribution of the magnetic flux along the entire pulley periphery and reducing the non-useful magnette leakage to a minimum.

In the magnetic nux pattern of the typical approximatelyy 1S" diameter pulley shown in Fig. l, the gauss readings at successive distances indicated by the dot-and-dash lines A, B, C, D and E and taken midway between the pole shoes 12 are approximately 500, 400, 250, 140 and 8O gausses respectively, and the corresponding gauss readings in the central radial plane of each group of magnets indicated bythe strong' zone dot-'and-dash line F are approximately 1,000, 540, 285, 170 and 90 gausses. With the prior patented pulley of the same diameter but utilizing Alnico magnets of considerably greater size, the corresponding gaussV readings midway between the successive pole-shoes- Y structure comprises in general, an elongated hollow cylindrical hub 8 having opposite end rings 9 secured thereto and being provided with inserts 10 secured to the end rings by cap screws 19; one or more annular series of radially disposed permanent magnets 21 `the inner ends of which snugly engage the external periphery of the huby Y S and the outer end 22 of each of which is tapered and constitutes a pole terminating at the pulley periphery; an

annular series of arcuate gap covers or spacers 23,k inter` posed between the successive radial magnets 21 and hav= ing inclined opposite end surfaces 24 wedgingly engaging" the tapered end poles 22 of the adjacent magnets; studbolts 2S secured to the hub 8 at the opposite sides of the magnets 2t and clampngly engaging the spacers' 23 te clamp the intervening magnets to the hub 8 and the gapcovers against the magnet poles; end heads 16 slidably embracing the inserts 10 and coacting with the opposite ends of the spacers 23; and elongated bolts 17 uniting the end heads 16 Within the spaces between the Successive magnets 21.

The central hollow hub 8^, rings 9', inserts 10,. end heads- 16 and assembly bolts 17' of the modifiednpulley are all of substantially the same construction as the coresponrcl-l ing parts of the pulley shown in Figs. l and A2; and the hub 8 of the modified structure iskform'ed of magnetic, material such as ordinary steel while the'magncts 21 are formed of highly magnetic material such as Alnico metal and the gap covers or spacers 23 vare constructed of,

non-magnetic material such as aluminum,- brass or plastic.l

The primary difference between the two pulleys is the,

omission of separate pole-shoes and the formation of the tapered poles 22 integral with the magnets 21 in the modi-v fication, and the' modied pulleys may also embody any desired number of the annular magnet series having the alined adjacent magnetsv 22 thereof in direct end toendcontact with each other as shown in' Fig. 4'. The4 spacers Y 23 of the modified assemblage may also extend throughout:

the effective length of the pulley,- and the studV bolts 25 serve to clamp the magnet blocks against thehub 8 while the bolts 17 clamp the spacer plates between the end heads 16. Y t v In the modified permanent magnetic pulley of similar size shown in Figs. 3, 4 and 5, the magneticzrux pattern` is substantially the same as that shown in Fig; l, evenV when magnets 21 of considerably smaller dimensions are utilized; The Ygauss readings in the modified structure;

and in the assemblage embodying narrow pole-shoes 22 are approximately alike, and the fields of maximum iniluence Vor strength are likewise confined to the poles 221 instead of to areas remote from these poles, thus again reducing the leakage losses toa minimum and insuring.

most effective distribution of the available magnetic energy. The magnets 21 of the modified pulley are aise.

adapted to be ground so as to snugly engage the hub 8 and the clamping surfaces 24 of the spacers 23, and the, parts may likewise be readily assembled or dismantled' by merely manipulating the studA bolts 2S, the boltslfl and the cap screws 19T.

From the foregoing. detailed description it should apparent that the present invention in fact provides ani improved permanent magnetic pulley wherein most eifers-V tive distribution of the available magnetic flux along the pulley periphery is obtained and in which undesirable magnetic leakage is reduced to a minimum. These results are attainable with magnets having reduced sizes of Alnico blocks which may be more readily dressed by grinding to properly cooperate with the cylindrical magnetic hub 8 and with the pole-shoes 12 or spacers 23, and the use of the cylindrical hub 8 also facilitates accurate construction and assembly of the improved pulley units in any desired lengths. In the modified assemblage it is unnecessary to provide separate pole-shoes for the magnet blocks; but in both of the embodiments illustrated and described, the improved results are obtained by providing poles of considerably less width than that of the spaces between the -successive magnet poles. The invention has proven highly satisfactory and successful in actual commercial use, and the improved pulleys may be manufactured in various sizes and for diverse uses.

It should be understood that it is not desired to limit the invention to the exact details of construction or to the precise mode of assembling and of utilizing the magnetic pulleys herein specifically illustrated and described, for various modifications Within the scope of the appended claims may occur to persons skilled in the art.

I claim: I

l. In a magnetic pulley, a hub of magnetic material having an annular series of permanent magnets radiating therefrom and provided with spaced magnet poles remote from the hub, and an annular series of non-magnetic spacers interposed between and cooperating with vsaid magnet poles to form the pulley periphery, said poles being of lesser width than the adjacent spacers measured circumferentially of the pulley periphery.

2. In a magnetic pulley, a hub of magnetic material having an annular series of permanent magnets radiating therefrom and provided with spaced magnet poles remote from the hub, au annular series of non-magnetic spacers interposed between and cooperating with said magnet poles to form the pulley periphery, said poles being of lesser width than the adjacent spacers measured circumferentially of the pulley periphery, and a series of radial members for maintaining said spacers in place and for clamping said magnets against said hub.

3. In a magnetic pulley, a hub of magnetic material having an annular series of permanent magnets radiating therefrom and provided with spaced magnet poles remote from the hub, and an annular series of non-magnetic spacers interposed between and cooperating with said magnet poles to form the pulley periphery, the Width of each pole being less than one-third of the width of each of the adjacent spacers measured circumferentially of the pulley periphery.

4. In a magnetic pulley, a circular hub of magnetic material having an annular series of permanent magnets radiating therefrom and provided with spaced magnet poles tapering away from the hub, and an annular senes of non-magnetic arcuate spacers interposed between said magnet poles and coacting therewith to cover the gaps between the successive magnets inwardly of the poles, each of said spacers being at least three times as wide as each magnet pole measured circumferentially of the pulley periphery whereby magnetic tlux zones of maximum intensity are produced directly adjacent to said poles.

5. In a magnetic pulley, a cylindrical hub of magnetic material, an annular series of permanent magnets having inner ends snugly engaging said hub and being provided with tapered outer ends, a non-magnetic spacer interposed between each adjacent pair of said outer magnet ends, and stud bolts radiating from said hub for maintaining said spacers in position and for clamping said magnets to the hub.

6. In a magnetic pulley, a cylindrical hub of magnetic material, an annular series of permanent magnets'havng inner ends snugly engaging said hub and being provided with tapered outer ends, a non-magnetic spacer interposed between each adjacent pair of said outer magnet ends, and stud bolts radiating from said hub for maintaining said spacers in position and for clamping said magnets to the hub, said outer magnet ends being less than one-half the width of said spacers measured circumferentially of the pulley periphery.

7. In a magnetic pulley, a cylindrical hub of magnetic material, an annular series of laterally spaced permanent magnets radiating from said hub and having outwardly tapering ends remote from the hub, a non-magnetic segmental spacer interposed between each adjacent pair of said outer tapered magnet ends, stud bolts radiating from said hub and coacting with said spacers and with said magnets to maintain the same in position, end heads slidably embracing said hub, and bolts coacting with said end heads to clamp said spacer plates in position.

8. In a magnetic pulley, a cylindrical hub of magnetic material, an annular series of permanent magnets radiating from said hub and having outwardly tapered magnet poles at their ends remote from the hub, non-magnetic spacers interposed between the successive magnet poles, and stud bolts connecting said hub and said spacers to clamp said magnets against the hub.

9. In a magnetic pulley, a cylindrical hub of magnetic material, an annular series of permanent magnets radiating from said hub and having outwardly tapered magnet poles at their ends remote from the hub, non-magnetic spacers interposed between the successive magnet poles, and stud bolts connecting said hub and said spacers to clamp said magnets against the hub, the outermost ends of said poles being less than one-third the width of each adjacent spacer and cooperating with the outer surfaces of the latter to provide the pulley periphery.

10. In a magnetic pulley, a cylindrical hub of magnetic material, an annular series of permanent magnets radiating from said hub and having outwardly tapered magnet poles at their ends remote from the hub, non-magnetic spacers illing the gaps between the successive magnet poles and having opposite edges clampingly engageable with the adjacent tapered poles, and clamping members radiating from said hub and coacting with said spacers to clamp said poles against the hub.

References Cited in the le of this patent UNITED STATES PATENTS 

